1. Field of the Invention
The present invention relates to a forklift which detect when its two prongs deviate from the horizontal and automatically corrects the posture of the prongs.
2. Description of the Prior Art
It is necessary to maintain the two prongs of a forklift in the horizontal at all times without being affected by the weight of the load. However, when a heavy load is put on the prongs, it is inevitable that the prongs sink forward, dropping the load. A forklift disclosed in Japanese Patent Laid-Open No. 39856/1976 is equipped with a tilt device which corrects the posture of the prongs. When the prongs are tilted, the device operates to restore the prongs to the horizontal. This device has a mast, and if this mast is vertical, it is assumed that the prongs are kept in the horizontal. Since such an assumption is made, the posture cannot be perfectly controlled. Accordingly, Japanese Utility Model Laid-Open No. 113198/1988 (Application No. 204173/1985) discloses a forklift equipped with a tilt-modifying means. The angle of the prongs to the body of the forklift is detected, and the operation of the modifying means is controlled according to the result of the detection. The prongs can be maintained in the horizontal by this technique, but when the center of gravity of the load deviates greatly right or left from the central position, the forklift cannot cope with this situation.